Regarding electric vehicles, I have been, from the start, clear: they’re not ready for prime time, primarily because they’re far too expensive, and because they aren’t yet flexible enough to replace contemporary gas powered vehicles. In addition, I’ve always had a major problem with paying taxes to support them. Government has no business choosing winners and losers in the marketplace, not with scarce tax dollars. EVs, for the most part, remain toys and greenie street cred—frequently expressed in a smug and insufferable manner—for the well-heeled, the top 7% of wage earners.

That said, I have also maintained that if you can afford them, and if they meet your needs, buy one. Heck, buy one for each day of the week and change them like underwear!

EV boosters have consistently argued that EVs are wonderful for the environment and sooooo much more efficient—in terms of resource utilization—than gas powered vehicles. I’ve endeavored over the years to explain those assumptions are, at the least, exaggerated, and in all likelihood, false.

A Tesla has the dual advantages, for the condescending set, of being both terribly expensive and highly efficient.

While one can’t argue the expense, or the cachet – de gustibus non disputandem est — is the Tesla really efficient? Electricity has to be generated somehow, and in the US, the vast majority of that generation is via hydrocarbon fuels – coal or natural gas. And most of what isn’t hydrocarbon is nuclear. And basic physics dictate it takes energy to convert energy from one form to another, and it takes energy to move energy, and frictional or resistive losses occur all along the way, and all other things being equal, it takes the same amount of energy to move 4500 pounds, whether you do so by electric motor or gasoline; the only difference is efficiency loss.

Given all that, I’ve long been suspicious of the notion that Teslas, or any electric cars, are more efficient than their gasoline counterparts. Gasoline is converted to movement only once, at the site of usage; electricity at least twice, and it has to be moved a long way to get from source to speed. Ever felt a long-distance power line? They get very hot. Resistance at work – and not the social justice kind.

So how much energy does it take to move a Tesla, say, 1000 miles, as opposed to a similarly-sized luxury car? Calculating the latter is fairly easy: using a roughly equivalent car (in size and status) as a baseline, a BMW 740i/Li, it gets (according to the DOE) 24 mpg combined, or 21/29 city/highway. 1000 miles /24MPG = 41.7 gallons.

Very straightforward. Now it gets interesting:

Now for the Tesla. A Tesla Model S uses about 38 KwH of power to go 100 miles, so to go 1000 miles, easy math, the car needs 380 KwH of electricity. The figures vary very little between city, highway and combined, because electric motors use no power when idling and are more linear in application. The main difference is air drag at speed.

Well, it’s not exactly ‘no power when idle.’ There’s a parasitic power loss. A Tesla uses power just sitting there, running its internal computers and whatnot [one huge whatnot: air conditioning, which is an enormous power drain]. Teslas used to consume 4.5 KwH per day standing still, but Tesla claims to have improved that to 1 KwH per day. There’s also the need to heat the battery, and heat the cabin; a gasoline motor uses waste heat for the latter and nothing for the former. Given that the average car is driven 15,000 miles per year, it would take 24 days to drive that far, so add another 24 KwH to the Tesla’s consumption for parasitic loss, and add another 5 KwH per day for battery heating and climate control over that period. (The EPA tests are measured with the car at operating temperature and the climate controls off.) So the Tesla uses 380 + 24 + 120 = 524 KwH over that time and distance.

That figure is not bad at electric power rates, but the issue is planetary efficiency – how green is it? How much fuel does a powerplant use to create that much electricity? The petroleum equivalent of that at the powerplant is 13.76 KwH per gallon of petroleum equivalent (figures from the EIA), so generating the power to move the Tesla that far takes 524/13.76 = 38.08 gallons.

But there’s many a slip ‘twixt the cup and the lip, and with electric cars there are several. First, transmission power loss consumes between 8% and 15% of the power just moving it from point of generation to point of use.

In California, the average figure is 9%. Add another 1% for the resistive power loss from where the power enters the home to when it gets to the Tesla’s charger. Let’s total it at 10%. So it takes 38.08 x 1.1 = 41.9 gallons to generate the amount of power the Tesla will use and then get it to the Tesla. But it takes even more than that, because the charging process itself is only about 85% efficient. (Tesla claims 91% efficiency, but real world experience seems to be more like 70 – 80%.) So 41.9 /0.85 = 49.28 gallons (678 KwH, if you were still counting those).

Whew. Regular readers know I was born without the math gene. I lack the ability to gaze lovingly at equations and suddenly find revealed the inherent order and beauty of the universe. While I understand what Mr. Karo is saying, I’ll take his calculations on faith. I trust the more mathematically inclined will be willing to add any necessary potential insights or corrections.

Liberals frequently care more about feelings than facts, and your smug Tesla-owning frenemy will never admit it, but in day to day usage, the big BMW is actually 18% more efficient, and 18% kinder to the planet. (Don’t get too cocky, Mr. 7 Series: at a US average 12 cents per KwH, the electricity cost to the Tesla owner for 1000 miles works out in total to about $81, as opposed to $98 for the gasoline. The reason the Tesla is less efficient, but still cheaper to run, is that the power company pays a lot less for fuel than the automobile driver does. But when the issue is green impact, not greenbacks, the BMW wins handily.)

What?!!! How can this be?! Not the sort of thing one sees in the politically correct press, is it?

Ah, but your frenemy retorts after mulling it over, ‘MY Tesla can run on solar power! And I can put solar panels on my roof! It’s free, I tell you! My S runs FREE!

Certainly not if it self-immolates, but let’s carry on:

Not really. The average solar panel produces about 10 watts per square foot. So some quick and dirty math: taking out of the equation the long-distance power transmission losses, and spreading out the power generation evenly over the time period, how much square footage would our Green Californian need to power his Tesla? 524 KwH for 24 days, as established above, plus 2% for transmission power loss at the solar panel and house level, and accounting for the 85% charger efficiency, you need 628,800 watt-hours. Dividing that by 24, you need 26,200 watt-hours per day.

You get about five hours of useful sun power production per day, so you need to get 5,240 watts per hour. You lose about 20% of your electricity in large systems; and accounting for the fact that the sun also doesn’t shine every day, add another 15% for reserve capacity, so you need 7,532.5 watts per hour capacity to account for efficiency losses and those rainy days. At top efficiency, that means you need 753 square feet of solar panels. At an installation price of $7 – $9 per watt (average of $8), the Green Man needs to spend over $60k for that much power. If he’s off the grid (i.e., stores the power instead of using net metering via his local utility), the storage system cost is on top of that. 753 square feet is a lot of ugly acreage, but it’s doable.

Of course, no self-respecting Green Weenie would settle for powering his car by the sun, but his house by Con Edison. And with the average efficient house using 1 KwH per hour, i.e., 24 KwH per day, the house needs 4.8 KwH capacity, and considering efficiency losses and reserve requirements, that means 6.9 KwH for the house. So to power both the Tesla and the house, Green Man needs at least 1,443 square feet of power production, at a cost of $115,000. But even using a Tesla-only setup, $60k would buy 25,641 gallons of gasoline (at the current US average price of $2.34 per gallon). The Big BMW could travel, on that much fuel, 24,000 x 24 MPG = 615,384 miles. Game, set and match – Munich and Detroit. Sad!

But hey, the federal government gives a $7500.00 tax credit for the purchase of every EV! But just for fun, and I mean fun, take this link to a clever SNL skit

hawking a new Mercedes AA class sedan, powered by 9648 AA batteries. SNL hasn’t been consistently funny for a very long time, but this ad, lampooning the self-important greenie mindset, is pitch perfect.

Electric vehicles are maturing through their adolescence, and just like in middle school, some members of the class are developing faster. Tesla and Chevrolet now have electric cars that will travel more than 200 miles per charge, but the vast majority of battery-powered cars are still limited to a 60-to-90-mile range. In the next decade, the electric car promises to blossom into something that doesn’t require sacrifices in practicality or price when compared with a gas-fueled car, but until the EV’s pimples clear up, we have plug-in hybrids.

With both a battery and a gas tank, plug-in hybrids strive to be everything to everyone, especially buyers who drive too much to deal with range limitations or who don’t want to spend much time plugged into a charger. The battery pack provides some electric-only operation while the gas tank and engine keep things moving when the ­battery is tapped. Chevrolet’s first Volt could travel 38 miles on its battery; after that, the engine would kick on to drive the car. Toyota, the leader in hybrid sales, also sold a plug-in version of its ubiquitous Prius; it featured a lithium-ion battery pack and could travel 11 miles on electric-only power before burning any gas.

Considering Mr. Karo’s analysis, and objective reality, C&D’s suggestion that EVs will be competitive in everyway with already efficient conventionally powered vehicles seems a bit optimistic. As I’ve noted in the past, there are three primary ways to improve mileage and/or overall efficiency: reduce weight, use fuel more efficiently, and/or improve aerodynamics. Of course, reducing weight too much makes vehicles inherently unsafe. More efficient fuel use, particularly where RVs are involved, requires technological breakthroughs not on the foreseeable horizon. Of course there might be a history-changing breakthrough in battery technology—or the discovery of some other previously unheard of exotic power source—tomorrow, but one shouldn’t count on it. And aerodynamic issues are likewise vexing. One can turn the family sedan into a formula one car, with all its aerodynamic wizardry, but they’re not terribly practical on family vacations, or trips to the grocery store for that matter.

The point is, improvements in all of those areas are incremental at best. Ford’s F150 is a case in point. In the 2016 model year, Ford changed to an all aluminum body, saving some 700 pounds of weight over steel-bodied trucks. This sounds impressive, and every little bit helps, but that’s the point: we’re talking little bits. Even so, the 2017 F150 weighs—according to Ford–from 4049 to 5236 pounds, dependent on options, 4WD, etc. Ford has saved about as much as is possible to save on a full sized pickup, and has optimized aerodynamics—a 4WD pickup can only be so aerodynamic and still be functional–and added even more fuel efficient engines, and fuel-saving tricks, but the fuel savings amount to only a few MPG under ideal conditions. That’s better than nothing, but still incremental savings.

But back to C&D. What have the stunning advances in technology wrought for the Volt and Prius?

Chevy’s and Toyota’s plug-ins are now entering their second generation, and both offer greater electric-only range and improved performance. Chevrolet’s Volt now has a larger, 18.4-kWh battery that weighs 21 pounds less than its predecessor’s, uses fewer cells, and delivers more than 40 miles of EV range. Inside the transaxle are two motor/generators. While the combined gas and electric power output is unchanged from the previous Volt, GM’s redesign of the motors and the gearbox increases efficiency and helps the new car shed 100 pounds.

When the battery reaches a predetermined low state in the Volt, the new ­aluminum-block 1.5-liter four with 101 horsepower starts up. This naturally aspirated engine runs in the Atkinson cycle for efficiency’s sake and is lighter than the iron-block 1.4-liter it replaces. Even when the Volt switches to hybrid mode, the battery isn’t completely depleted. By leaving some electricity in reserve, the electric motors can add to the four-cylinder’s 101 horses to ensure that the Volt maintains the same 149 horsepower no matter the mode.

Toyota’s second-gen plug-in Prius (rechristened the Prius Prime) follows the Volt’s tack. Toyota doubled the battery capacity to 8.8 kWh, which more than doubles the range to 25 miles. The lithium-ion battery pack lives under the cargo area and powers the two electric motor/generators inside the trans­axle, which can combine for 68 kW of output, or 91 horsepower. That’s a far more useful number than the old Prius Plug-In’s 51-hp electric-only effort.

When the juice stops flowing in the Prius Prime, a 1.8-liter Atkinson-cycle four with 95 horsepower makes its entrance. As in the Chevy, Toyota leaves some battery capacity in reserve to allow the electric motors to contribute to acceleration and support the gasoline engine. Unlike the Volt, though, the Prius Prime makes more power in hybrid mode than in EV mode, or 121 combined horsepower.

Tesla Model S and Supercharger station.credit: caranddriver.com

Forgive me, gentle readers, for being underwhelmed, but Chevy was advertising the Volt’s battery range as up to 50 miles when it was first introduced. Practical mileage has been in the 25 mile range, so it seems not much has changed despite the engineering marvels C&D so breathlessly lauds. And of course, charging times have not meaningfully decreased, while fast chargers remain expensive. Likewise, publically accessible chargers out there in the wide world remain rare and primarily limited to a few regions.

In any case, if you’re interested, take the link and read the whole review. I’ll add a spoiler: C&D thinks the Volt is much slicker than the Prius.

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7 thoughts on “Electric Vehicles: An Adventure In Tesla Math”

All of the losses of tens of millions of jobs in the heavy industrial sector
came about due to the insane energy policies starting with Carter, wildly
expanded under Clinton, and reaching surreal levels under Obiteme!
That is the ridiculous notion that one can “Conserve” one’s way to
energy independence.

If we put together just a few simple facts, we can refute this idiotic
assumption; We have not built one net new watt of power plant capacity
in about 40 years. During this same time, when we have expanded
generating capacity through replacement, it has been at the expense of
truly clean energy like nuclear. Meanwhile, the population continued to
grow right along with the demand for good paying jobs! The “New economy,”
consisting mainly of service sector jobs needed cars to get to work, and
low utility rates in order to raise a family on a Starbucks minimum wage.
High energy prices disproportionately affect the poor. DUH!

Excluding natural gas, which produces mostly harmless CO2, that leaves
us with coal, which produces most of the energy we consume in America.
This is where the story gets even more bizarre: Replacing proven clean
sources like nuclear and natural gas with solar and wind power actually
resulted in the creation of more pollution, not less!

If you look at the “Alternative” sources of energy, it becomes clear that
solar and wind are the two MOST expensive and least efficient forms of
energy in existence. Peak solar: About 4 hours a day. The 12 hours of
daylight are not steady. Add maintenance downs and overcast days,
and you get my point. Wind power? Same problem, the wind doesn’t
blow at a constant velocity.

I have driven to job sites near the Tehachapi windmill farms. On any given
day, 25+ percent of them are not turning. These pieces of crap are so
expensive to repair, the companies that run them are allowing them to
rot. Once the government subsidies expire, they are not going to replace
major components if they require heavy lift helicopters to replace them.

Think about distributed power for a moment. Our first digital computers
involved thousands of vacuum tubes. I used to maintain lighting in a paper
mill (Acres under a roof.) On any given day, 10% of the fluorescent fixtures
were FUBAR. I could get in a scissor lift and replace tubes and ballasts.
How does one deal with a 10,000 pound gearbox or an 8,000 pound
generator 300 freaking feet in the air!

In Canada, it was discovered that it was so expensive to repair these
monstrosities, even salvage companies were taking a pass on
demolishing these worthless pieces of shit! I doubt that even High
Desert Meth addicts would take on the job.

That leads me to my final points; In order to make up for the inefficiency
of wind and solar, power companies are REQUIRED to keep natural gas
and coal plants spooled up to take up the load in the event these “renewable”
sources fail. I have worked on air and gas compressors, steam turbines,
gearboxes, fans, blowers, and a lot of shit most people have never even
heard of!

One of these was A 747 GE jet engine that drove a 35 mw generator in
a paper mill. One of the greatest concepts in energy generation was highly
distributed. CoGeneration was the wave of the future! We got to sell 35mw
to So Cal Edison, and use the exhaust heat to create steam for the process.
Our ten or 12 mw electric bill was paid, we used the HP steam to drive our
turbines, and dried the paper in our process and still made a profit!

The liberal politicians in Sacramento even managed to screw this up! I
worked on an instrumentation issue at St. John’s Hospital CoGen. They
were becoming so common, even a small dairy in Lakewood had one.

If you think I am out of my mind, consider the following: The liberal idiots
came up with this batshit crazy concept: The “Pumped storage” concept:
After inflating energy prices to an astronomical level, the wealthy corporate
donors to the Democrats created a hydroelectric process process that
pumped water up to a reservoir in off in peak hours, so that they could
take advantage of artificially inflated “Peak hour rates” by letting it flow
back through hydroelectric generators. Can you Spell Perpetual
Motion Machine?

The cost to pump the water up to the reservoir was so high, the only way
they were allowed to make a profit was that the government was bribing
them with tax dollars! This is not so much as a case of liberal idiocy as
it is a cause of liberal corruption. Much like Solyndra, they sucked up tens
of millions in campaign donations (AKA BRIBES!)

In 1896, the Robert’s Electric Car got about 40 miles on a charge. That is
just about the same mileage as the Chevy Volt got just a few years ago.
Buy an electric car, and the ONLY thing you are doing is shifting the
NO, SO2 and other REAL pollutants to the power plants run by evil
corporations that liberals are hell bent on destroying! In other words,
all electric cars are powered by coal.

This is quite the unusual situation in that there are three or four elephants in the room instead of the traditional lonely individual.

One of them is what are you going to do with all the gasoline? About half of crude oil is refined into gasoline. The other half goes into more than 10,000 other products (diesel, fuel oil, aviation fuel, asphalt, lubricants, plastics, pharmaceuticals,…). If you can’t sell the gasoline then the price of all the other products go up and the supply will go down.

Another is infrastructure. Domestic electricity is distributed at a high voltage. Transformers are used to reduce the voltage to 220/110. The average usage is one transformer per ten houses. Electric cars would require one transformer for every three houses. Huge costs and years of construction in every neighborhood.

Thanks! Many people don’t know what those gray, trashcan-like things are hanging on utility poles around their neighborhoods, until one blows out, sometimes explosively. Electricity has to come from somewhere. It isn’t magically sucked out of the air, ala Nicola Tesla.